Piezo-electric phonograph pick-up



June 3, 1930. c w, HQUGH 1,761,831

PIEZO ELECTRIC PHONOGRAPH PICKUP Filed Sept. 22, 1926 UIIIIIIIIUJIHW INV EN TOR.

I Patented June 3, 1930 UNITED STATES PATENT OFFICE f CLINTON w. HO'UGH,OE BOONVIL LE, NEW YORK, ASSIGNOR, BY MESNE ASSIGNMENTS,

TO FEDERAL TELEGRAPH COMPANY, A CORPORATION OF CALIFORNIA IPIEZO-ELECTBIC PHONOGRAIPH PICK-UP Application filed September 22, 1926.semi- No. 137,129.

My invention relates broadly to the reproductlon of sound, and moreparticularly to a phonograph pickup or microphone.

My invention resides in a method of mounting a piezo electric crystalelement for the effective utilization of its piezo electric propertiesin translating the vibratory -movements of a phonograph stylus ordiaphragm pulses.

The object of my invention is to provide a practical construction ofmounting for a piezo electric crystal element which is used as aphonograph pickup or micro hone in the reproduction of soundsubstantially free of distortion.

Another object of my invention is to provide a construction of piezoelectric phonograph pickup or microphone wherein a piezo electriccrystal element is provided with terminal caps at opposite ends thereofwith one end of the piezo electric crystal element mounted in stationarymanner and the other end arranged to be vibrated in accordance with themovement of a phonograph stylus for mechanically stressing the piezoelectric crystal element and setting up corresponding electrical chargestherein, which may be utilized in the operation of an electricalreproducing system. a

My invention will be more fully understood from the specificationhereinafter following by reference to the accompanying drawings inwhich:7 i

Figure 1 is a side elevation of the mounting for the piezo electriccrystal element; Fig. 2 is a cross-sectional view taken through themounting of the piezo electric crystal element; and Fig. 3 is a frontview of the piezo electric crystal element supported in the mounting ofmy invention.

Referring to the drawings in detail refer:

ence character 1 represents a yoke mounting with a sleeve 2 to fit thestandard phonograph tone arm 3; 4 is a set screw to fasten the yoke inplace on the tone arm and to permit adjustment of the angle at which thephonograph needle 5 rests upon the phonograph record 6. .The piezoelectric element 7 is mounted in two conducting into correspondingelectrical im-'- cord by means of needle or stylus 5. Both terminals 2and 3, which fit snugly around the ends of the element 7. The upperterminal 8 is rigidly attached to the upper arm of the yoke 1 andconsequently holds the upper end of the piezo electric element. 7 in arigid position. The lower terminal 9 is rigidly attached to the needleholding armature 10 which is mounted upon pivot screw Hand is vibratedby the phonograph rethe upper terminal 8 and the lower terminal 9 arecup shaped-caps which closely fit over the upper and lower endsrespectively of the piezo electric element 7, Pivot screw 11 serves as apivot upon which armature 10 vibrates and as an adjustment to compressthe piezo electric element to the, point of highest efliciency. Iivotscrew 11 is locked into position by lock nut 12. Pivot screw 11 servesto complete the electrical connection between the upper and lower endsof the piezo electric element through terminal 8, yoke 1, pivot screw 11and terminal 9. Yoke 1 serves as one output terminal of the device. Thesecond terminal consists of a conducting band or girdle 13 aflixedaround the surface of the center of the piezo electric element, andwrapped by a connecting wire member 14. This construction causes thevibrations of "the phonograph needle to. be transmitted to the piezoelectric element in the form of torsional stresses which generatecorresponding electrical impulses at the terminals of the piezo electricelement. T-hese electrical impulses are utilized to operate responsivedevices such as telephones or amplifiers, loud speaker equipment, andthe like.

While I have described a preferred form of the invention, I desire it tobe understood that modifications may be made and that no limitationsupon the invention are intended other than are imposed by the scope ofthe appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is as follows:

1. In a piezo electric phonograph pick-up, a piezo electric crystalelement having piezo electrically active faces at its opposite ends, 100

a conductive cap closely conforming to the piezo electrically activeface at each end of said crystal element, a yoke member including a pairof arms extending parallel to 5 the plane of said conductive caps, oneof said conductive caps being secured to the inner face of one of saidarms, a screw device extending through the opposite one of said arms toa position adjacent the other one of said conductive caps, and meansconnected to said last mentioned conductive cap for impressingmechanical vibrations on said piezo electric crystals for the generationof electrical energy therein, according to the impressed vibrations.

2. In a piezo electric phonograph pick-up device, a piezo electriccrystal element, a cap embracing the sides of said piezo electriccrystal element adjacent each end thereof and abutting with each endsurface of the piezo electric crystal element, a conductive memberembracing each of said caps and rigidly secured to one of said caps,means extending through said conductive member in alignment with theother of said end caps for mounting said piezo electric crystal elementin said conductive member under a predetermined pressure, a styluscarrier connected to said last mentioned end cap for subjecting saidpiezo electric crystal element'to mechanical vlbration for thegeneration of electrical energy in accordance with the impressedvibrations.

3. A phonograph pick-up device comprising a yoke having a pair ofparallel extending arms, a piezo electric crystal elementhaving aconductive ca on each end of said element, the conductive cap at one,

40 end of said element lying in abutment with one of said parallelextending arms, an angularly bent member having a flattened surface inabutment with the end cap at the opposite end of said piezo electriccrystal element, an adjusting screw passing through the other of saidparallel extending arms and having a conical shaped end entering adepression in the flattened surface of said angularly bent member, and astylus carried 5 by said angularly bent member for imparting mechanicalvibrations to the end of said piezo electric crystal element.

In testimony whereof I aflix my signature.

CLINTON W. HOUGH.

